Hi,
Depending on the cause of the leak there may be a seal kit, or if the issue is deeper it may be more complicated as already described by skyreach.
You can contact Combilift spare parts either for assistance.
As you are based in the UK, you can contact the UK Technical Team by completing a quick technical support form at the bottom of the main combilift.com web site or direct link https://warranty.combilift.net/technical-support-form/. The form only asks for the minimal info so the team can quickly help you. There is no login required and no charge for this support.